1. Field of the Invention
The present invention relates to a composition for removing conductive materials. More particularly, the present invention relates to a composition for removing all of aluminum, molybdenum and indium tin oxide and a manufacturing method of an array substrate using the same.
2. Discussion of the Related Art
Liquid crystal display devices are widely used flat panel display devices. A liquid crystal display (LCD) device includes an upper substrate, a lower substrate and a liquid crystal layer interposed therebetween. Electrodes are formed on the upper substrate and the lower substrate, respectively. When a voltage is applied to the electrodes, an electric field is induced between the electrodes. Liquid crystal molecules of the liquid crystal layer are rearranged according to the electric field to thereby control the transmittance of light through the liquid crystal molecules.
FIG. 1 is a cross-sectional view of an array substrate for an LCD device according to the related art.
As shown in FIG. 1, a gate electrode 14 is formed on a transparent substrate 12 by depositing a first metal layer and then patterning it through a first mask process. The first metal layer may include a conductive metallic material, such as aluminum (Al), an aluminum alloy such as AlNd, molybdenum (Mo), tungsten (W) or chromium (Cr). An aluminum alloy, such as AlNd, having a low resistivity may also be included. The gate electrode 14 may also have a double-layered structure including an aluminum alloy, such as AlNd, and molybdenum (Mo) as illustrated. Although not shown, in the first mask process, a photoresist (PR) layer is formed on the first metal layer. The PR layer may be a positive type PR in which a portion exposed to light is removed after developing or a negative type PR in which a portion not exposed to light is removed after developing. A mask including a light-transmitting portion and a light-blocking portion is disposed over the PR layer. The PR layer is exposed to light through the mask and then is developed to form a PR pattern selectively exposing the first metal layer. The first metal layer may be wet-etched or dry-etched by an etchant using the PR pattern as an etching mask, and thus the gate electrode 14 is formed. Next, the PR pattern is removed through a process, such as an ashing process or a stripping process.
A gate insulating layer 16 is formed on the substrate 12 including the gate electrode 14 thereon. The gate insulating layer 16 may include an inorganic insulating material, such as silicon nitride (SiNx) or silicon oxide (SiO2).
An active layer 18, an ohmic contact layer 20 and source and drain electrodes 22a and 22b are formed on the gate insulating layer 16 by depositing and then patterning an intrinsic amorphous silicon layer, an impurity-doped amorphous silicon layer and a second metal layer through a second mask process. The second metal layer may include molybdenum (Mo). In the second mask process, a PR layer is formed on the second metal layer, and a mask is disposed over the PR layer. The PR layer is exposed to light through the mask and then is developed to form a PR pattern selectively exposing the second metal layer. The second metal layer may be wet-etched or dry-etched by an etchant. The impurity-doped amorphous silicon layer and the intrinsic amorphous silicon layer may be sequentially dry-etched to thereby form the active layer 18, the ohmic contact layer 20 and the source and drain electrodes 22a and 22b. Here, the etchant may be a solution including hydrogen peroxide (H2O2). Next, the PR pattern is removed by a process, such as an ashing process or a stripping process.
A passivation layer 24 is formed on the substrate 12 including the active layer 18, the ohmic contact layer 20 and the source and drain electrodes 22a and 22b by coating a transparent organic insulating material, such as benzocyclobutene (BCB) or acrylic resin, or depositing an inorganic insulating material, such as silicon nitride (SiNx) or silicon oxide (SiO2). The passivation layer 24 is patterned through a third mask process to thereby form a contact hole 26 exposing a part of the drain electrode 22b. 
A pixel electrode 28 may be formed on the passivation layer 24 by depositing a transparent conductive material such as indium tin oxide (ITO) and then patterning it through a fourth mask process. The pixel electrode 28 contacts the drain electrode 22b via the contact hole 26. The fourth mask process may include a wet-etching process or a dry-etching process similar to the first and second mask processes. In the fourth mask process, a nitrohydrochloric acid or an oxalic acid may be used as etchant for forming the pixel electrode 28.
As described previously, an array substrate for a liquid crystal display device may be manufactured through four-mask processes. Because different kinds of etchant are used in respective mask processes for forming the metallic patterns, such as the gate electrode 14, the source and drain electrodes 22a and 22b and the pixel electrode 28, various facilities are required. Accordingly, productivity is lowered, and costs for the facilities are increased.